The present invention relates to liquid dispersion polymer compositions which comprise a dispersed polymer phase, a continuous carrier phase and a surfactant, their preparation and the use of these liquid dispersion polymer compositions to prepare microparticulate thickening systems which thicken aqueous or aqueous/organic compositions. More particularly it relates to liquid dispersion polymer compositions which comprise microparticles of a hydrophilic, water soluble or swellable polymer, preferably an acrylic-based polymer, which is dispersed in a silicone polymer fluid carrier phase and an oil-in-water surfactant, their preparation and the use of these liquid dispersion polymer compositions to prepare microparticulate thickening systems to thicken aqueous or aqueous/organic compositions, particularly for use in personal care and pharmaceutical formulations.
Thickeners are used extensively in personal care formulations such as cosmetic and pharmaceutical formulations, to affect the aesthetics, product application and suspension and delivery of the active raw materials. Polymeric thickeners have been used for this purpose for many years. The types of polymeric thickeners that have been used range from natural gums such as guar, through modified natural materials such as hydroxyethyl cellulose, to synthetic thickeners such as the Carbomers(copyright) based on polyacrylic acids.
The Salcare(copyright) range of liquid dispersion polymers, available through Ciba Specialty Chemicals, is a range of microparticulate acrylic-based polymeric thickeners in a hydrophobic carrier medium. Salcare(copyright) SC91 is an anionic thickening agent based on a sodium acrylate polymer and mineral oil carrier with PPG-1 trideceth-6 as the activator surfactant. Salcare(copyright) SC92 is a cationic copolymer thickener and conditioner comprising polyquaternium 32 and mineral oil. Salcare(copyright) SC95 and Salcare(copyright) SC96 are cationic homopolymer thickeners and conditioners. Salcare(copyright) SC95 comprises polyquaternium 37 in mineral oil with PPG-1 trideceth-6. Salcare(copyright) SC96 comprises polyquaternium 37 in propylene glycol dicaprylate dicaprate with PPG-1 trideceth-6. Salcare AST is an anionic thickening agent based on a sodium acrylate polymer in soya bean oil with PPG-1 trideceth-6.
The tiny, spherical microparticles of the above hydrophilic acrylic polymers, whether anionic or cationic in charge, have a typical particle size in the range of 0.1-2 microns, with an average particle size in the range of 0.5-1.0 microns. The polymer microparticles are preferably manufactured by methods in which water soluble vinyl addition monomers are polymerized utilizing a water-in-oil polymerization route.
On stirring of any of the above liquid dispersion polymers into an aqueous system, the activator surfactant converts the hydrophobic carrier into an oil-in-water emulsion. By the term xe2x80x9cactivator surfactantxe2x80x9d is meant a surfactant which activates the conversion of the hydrophobic carrier into an oil-in-water emulsion. At the same time the hydrophilic polymer expands on exposure to water but does not dissolve, resulting in a smooth and rapid viscosity increase. Typically the polymer particles swell to give a microparticulate thickening system comprising polymer particles having a typical particle size in the range of 2.5-5 microns in diameter. Since the water molecules move into the small polymer particles by osmosis, the osmotic effect experienced by the polymer particle is a balance between water and any electrolyte present in the system. Hence high electrolyte levels reduce the swelling of the polymer particles.
The microparticulate thickening systems have a pseudoplastic rheological profile which gives good stability and suspension characteristics at low shear rates (such as those experienced by the product on standing), and low apparent viscosity""s at high shear rates, which corresponds to excellent rub-in characteristics.
As previously mentioned, the continuous organic carrier phase for the above Salcare(copyright) liquid dispersion polymers is provided at least in part by a silicone polymer fluid.
In one aspect the present invention provides a liquid dispersion polymer composition comprising a hydrophilic, water soluble or swellable polymer as a dispersed polymer phase, a silicone polymer fluid as a continuous carrier phase and an oil-in-water surfactant, wherein the polymer is in the form of microparticles having an average particle size in the range of 0.1 to 2 microns.
Typically the liquid dispersion polymer composition comprises
a) from 35% to 65% by weight of the polymer,
b) from 20% to 50% by weight of a silicone polymer fluid, and
c) from 5% to 25% by weight of a surfactant or a surfactant mixture, each based on the total weight of the composition.
Advantageously the hydrophilic polymer a) is water swellable, i.e. it is sufficiently cross-linked to swell but not dissolve in water. Preferably it is acrylic-based. Also it is preferably anionic or cationic.
The silicone polymer fluids b) are well known to the cosmetic industry and have been used for many years in hair and skin formulations. They are particularly favored over mineral oils for their improved aesthetic feel on skin and hair and also for the sheen they impart when employed in hair care applications. The products of the instant invention provide a compatibility across the different ionic systems and give a level of formulation versatility using silicone technology that is not provided by any other liquid dispersion polymer.
Preferably the surfactant mixture c) comprises both surfactants useful in the manufacture of the microparticles of swellable polymer a), and at least one surfactant which serves as the activator for the subsequent oil-in-water microparticulate thickening emulsions. This activator surfactant for the oil-in-water thickening emulsions comprises from 1.0% to 10.0% by weight of the composition, preferably from 2.0% to 8.0% by weight of the composition. Preferably the activator surfactant is a nonionic oil-in-water emulsifier having a HLB generally above 7. Suitable emulsifiers of this type are well known to those skilled in the art. Ethoxylated alcohols are preferred.
Additionally the composition may contain minor amounts of other components which do not affect its essential characteristics. Typically these other components may include up to about 3% by weight each of water and volatile organic solvents as well as small amounts of other components which are left over from the preparation of the water soluble or swellable polymers.
Advantageously the composition comprises
a) from 40% to 60% by weight of the polymer, wherein the polymer is anionic or cationic and is water swellable,
b) from 25% to 45% by weight of a silicone polymer fluid, and
c) from 8% to 20% by weight of a surfactant or a surfactant mixture, each based on the total weight of the composition.
A particularly preferred composition comprises
a) from 45% to 58% by weight of the polymer, wherein the polymer is anionic or cationic and is water swellable,
b) from 30% to 40% by weight of a silicone polymer fluid, and
c) from 10% to 18% by weight of a mixture of surfactants, each based on the total weight of the composition.
A very particularly preferred composition comprises
a) from 45% to 58% by weight of the water swellable polymer, wherein the polymer is cationic,
b) from 32% to 38% by weight of a silicone polymer fluid,
c) from 12% to 18% by weight of a mixture of surfactants, each based on the total weight of the composition.
Still another aspect of the present invention is the provision of thickened aqueous or water-containing compositions, in particular personal care formulations, which comprise
a) 0.1% to 8% by weight, preferably 1% to 6% by weight of a liquid dispersion polymer composition as described above,
b) 0.1% to 70%, preferably 2% to 35% by weight of additional ingredients, for example personal care ingredients such as cosmetic or pharmaceutical excipients and/or active ingredients and
c) 45% to 99% of water or a mixture of water and a water-miscible organic solvent such as a lower alcohol.
Such lower alcohols include ethanol, isopropyl alcohol, propylene glycol, di-isopropyl alcohol and other known lower alcohols.
These compositions may be in the form of lotions, creams, salves, gels, milks, sprays, foams or ointments.
The additional components can be any ingredient which may form part of a thickened aqueous emulsion of the oil-in-water type. Non-limiting examples of cosmetic ingredients include: antimicrobials (such as triclosan xe2x80x9cRTMxe2x80x9d, farnesol xe2x80x9cRTMxe2x80x9d); skin conditioning agents and emollients such as lanolin and derivatives thereof; esters such as iso-propyl propanoate, decyl oleate, isopropyl isostearate, trioctanoin, triisostearin, myristyl propionate; fatty alochols; squalene; silicones such as cyclomethicone, dimethicone, dimethicone copolyol; acetamide monoethanolamine; dimethyl polysiloxane; moisturizers such as aloe vera, barrier creams, emollients, alpha and beta hydroxy acids such as lacti acid and glycolic acid; anti-inflammatory actives like allantoin and bisabolol; UV sun screening agents such as para aminobenzoic acid, octyl salicylate, and octyl methoxycinnamate, xe2x80x9csunlessxe2x80x9d tanning agents, whitening agents, insect repellents, essential oils such as patchouli oil, peppermint oil, rosemary oil, citronella oil, tea tree oil, orange or lemon oils, cedarwood oil and sandalwood oil, vitamins, colours and pigments; hair conditioners such as amodlmethicone, cyclomethicone, panthenol, lauramide diethanolamine, lauramine oxide and silk protein; perfume components; hair dyes and bleaches and preservatives such as methyl-, ethyl-, propyl-paraben and imidazolidinyl urea.
Pharmaceutically active ingredients may vary widely and include all therapeutic agents intended for topical application to the skin or hair, in particular substances to treat itching, tingling, scaling, inflammation or infection of the skin, burns, and scalp hair loss of humans or other mammals.
Still another aspect of the present invention is the provision of a method for the preparation of a therapeutic lotion, cream, salve, gel or ointment which comprises mixing 0.1% to 8% by weight, preferably 1% to 6% by weight of a liquid dispersion polymer as described above into an aqueous or aqueous/organic composition which contains from 0.1% to 70% by weight of at least one therapeutic agent and/or excipient.
Still another aspect of the present invention is the provision of a method for the topical treatment of the skin, which comprises applying a composition as defined above to the skin, face or scalp of a human being or other mammal in need of such treatment. The type of treatment will depend on the active ingredient(s) dissolved or suspended in the composition. For example the composition may comprise facial creams such as barrier cream, a moisturizer cream, lotion or milk, a cleanser or toner, a hand and body milk or lotion, a body spray, creams, lotions or milks containing sun-screens against UV-A and UV-B radiation, a xe2x80x9csunlessxe2x80x9d tanning cream, lotion or spray, a skin bleaching cream, lotion or spray, a depilatory cream, a hair conditioning cream, lotion or shampoo, a hair dyeing cream or lotion, a pre- or aftershave cream, lotion, gel or balm, a disinfectant cream, lotion, ointment or gel, a soothing cream, lotion or spray as an after sun application for sunburn, etc.
Other aspects of the present invention will become apparent from the following discussion and the examples. The examples merely illustrate certain aspects of the invention and are not intended to be limiting thereof.